Instant Interrupts - Revisited

[sayzer]

Hi DT,

When @ INT_DISABLE TMR0_INT command is used @4Mhz 16F628A, can you estimate how long does it take to process it and eventually disable it?

uS?


Thanks.

[Darrel Taylor]

Hi Sayzer,

For 14-bit chips,
It takes 1 instruction cycle to disable the interrupt and depending on what bank it's in at the time, it may take 1 or 2 instructions to change to the correct bank before disabling.

So @ 4mhz, it could take from 1 to 3 uS.

On 18F's, it's always just 1 instruction.
<br>

[sayzer]

Hi Sayzer,

For 14-bit chips,
It takes 1 instruction cycle to disable the interrupt and depending on what bank it's in at the time, it may take 1 or 2 instructions to change to the correct bank before disabling.

So @ 4mhz, it could take from 1 to 3 uS.

On 18F's, it's always just 1 instruction.
<br>

I assume your answer would be the same for other sources of interrupt (other then TMR0).
In any case, 3 uS is more then good enough for my case.

Thanks very much DT.

[mister_e]

Not sure if this have been covered, but however. I'm actually working with a PIC16F616, there's no interrupt on PORTB change on this one, but Interrupt on PORTA change, great Microchip

From what i see, it is not included in DT_INTS-14, so here's one method to do so...

Open DT_INTS-14, and add the sections in Red

ASM
  #define INT_INT   INTCON,INTF     ;-- INT External Interrupt
  #define RBC_INT   INTCON,RBIF     ;-- RB Port Change Interrupt
  #define RAC_INT   INTCON,RAIF     ;-- RA Port Change Interrupt
  #define TMR0_INT  INTCON,T0IF     ;-- TMR0 Overflow Interrupt 16F
  #define TMR1_INT  PIR1,TMR1IF     ;-- TMR1 Overflow Interrupt
  #define TMR2_INT  PIR1,TMR2IF     ;-- TMR2 to PR2 Match Interrupt
  #define TX_INT    PIR1,TXIF       ;-- USART Transmit Interrupt
  #define RX_INT    PIR1,RCIF       ;-- USART Receive Interrupt
  #define CMP_INT   PIR2,CMIF       ;-- Comparator Interrupt
  #define EE_INT    PIR2,EEIF       ;-- EEPROM/FLASH Write Operation Interrupt
  #define BUS_INT   PIR2,BCLIF      ;-- Bus Collision Interrupt
  #define PSP_INT   PIR1,PSPIF      ;-- Parallel Slave Port Read/Write Interrupt
  #define AD_INT    PIR1,ADIF       ;-- A/D Converter Interrupt
  #define SSP_INT   PIR1,SSPIF      ;-- Master Synchronous Serial Port Interrupt
  #define CCP1_INT  PIR1,CCP1IF     ;-- CCP1 Interrupt
  #define CCP2_INT  PIR2,CCP2IF     ;-- CCP2 Interrupt

ENDASM

asm
INT_Source  macro  IFR, IFB, IER, IEB
    if ((IflagReg == IFR) && (IflagBit == IFB))
  list  
INT_Flag_Reg = IFR
INT_Flag_Bit = IFB
INT_Enable_Reg = IER
INT_Enable_Bit = IEB
Found = YES
    endif
;  nolist  
    endm 
endasm


asm
;-------------------------------------------------------------------------------
GetIntInfo  macro  IflagReg, IflagBit

Found = NO
; nolist
  ifdef INTF    ;----{ INT External Interrupt }----------------[INTCON, INTF]---
      INT_Source  INTCON, INTF, INTCON, INTE
  endif
  ifdef RBIF    ;----{ RB Port Change Interrupt }--------------[INTCON, RBIF]---
      INT_Source  INTCON, RBIF, INTCON, RBIE
  endif
  ifdef RAIF    ;----{ RA Port Change Interrupt }--------------[INTCON, RAIF]---
      INT_Source  INTCON, RAIF, INTCON, RAIE
  endif
  ifdef T0IF    ;----{ TMR0 Overflow Interrupt }-------------[INTCON, TMR0IF]---
      INT_Source  INTCON, T0IF, INTCON, T0IE
  endif
  ifdef TMR1IF  ;----{ TMR1 Overflow Interrupt }---------------[PIR1, TMR1IF]---
      INT_Source  PIR1, TMR1IF, PIE1, TMR1IE
  endif
  ifdef TMR2IF  ;----{ TMR2 to PR2 Match Interrupt }-----------[PIR1, TMR2IF]---
      INT_Source  PIR1, TMR2IF, PIE1, TMR2IE
  endif
  ifdef TXIF    ;----{ USART Transmit Interrupt }----------------[PIR1, TXIF]---
      INT_Source  PIR1, TXIF, PIE1, TXIE
  endif
  ifdef RCIF    ;----{ USART Receive Interrupt }------------------[PIR1 RCIF]---
          INT_Source  PIR1, RCIF, PIE1, RCIE
  endif
  ifdef CMIF    ;----{ Comparator Interrupt }--------------------[PIR2, CMIF]---
      ifdef PIR2
          INT_Source  PIR2, CMIF, PIE2, CMIE
      else
          INT_Source  PIR1, CMIF, PIE1, CMIE
      endif
  endif
  ifdef EEIF    ;---{ EEPROM/FLASH Write Operation Interrupt }---[PIR2, EEIF]---
      ifdef PIR2
          INT_Source  PIR2, EEIF, PIE2, EEIE
      else
          INT_Source  PIR1, EEIF, PIE1, EEIE
      endif
  endif
  ifdef BCLIF   ;----{ Bus Collision Interrupt }----------------[PIR2, BCLIF]---
      INT_Source  PIR2, BCLIF, PIE2, BCLIE
  endif
  ifdef PSPIF   ;--{ Parallel Slave Port Read/Write Interrupt }--[PIR1, PSPIF]--
      INT_Source  PIR1, PSPIF, PIE1, PSPIE
  endif
  ifdef ADIF   ;----{ A/D Converter Interrupt }------------------[PIR1, ADIF]---
      INT_Source  PIR1, ADIF, PIE1, ADIE
  endif
  ifdef SSPIF  ;----{ Master Synchronous Serial Port Interrupt }--[PIR1, SSPIF]-
      INT_Source  PIR1, SSPIF, PIE1, SSPIE
  endif
  ifdef CCP1IF ;----{ CCP1 Interrupt }-------------------------[PIR1, CCP1IF]---
      INT_Source  PIR1, CCP1IF, PIE1, CCP1IE
  endif
  ifdef CCP2IF ;----{ CCP2 Interrupt Flag }--------------------[PIR2, CCP2IF]---
      INT_Source  PIR2, CCP2IF, PIE2, CCP2IE
  endif
    
  list
    endm
  list  
ENDASM

Sure enough there's some other PIC with interrupt on PORTA change, I just never came across one... or maybe... but never used that feature yet

[HankMcSpank]

Oops - double post....removed.

[HankMcSpank]

mister_e.... I'd like to get interupts working on my 16F690 ....I visited Darrel's website & on the very first example "Hello World", he shows the code along with a short schematic - the interupt is showing as being presented on port RBO (actually called RBO/INT on the diagram).

I have some (newbie!) questions...

Are Darrel's interput routines for a specific PIC?

I ask because my PIC 16F690 doesn't even have an RB0(!), therefore to my next question....

Is there a particular PIC pin I should be using for his routines to work.

My end goal is quite simple...I have an encoder wheel with 48 black stripes that I'm having one helluva job getting the polling right....I'd simply like to be able to use a PIC interupt for when each black stripe passes the photo transistor 'pickup' (to increment a PIC counter)

That said, for testing puproses I do need one more interupt ...this being for a magnetic switch (I've glued a magnet to the edge of the disc so I know when the wheel has turned once) to interupt once per rev, I can then make sure that the PIC 'saw' all the stripes for the past rev....so to my other question - is there normally just one INT pin that's useable for externally triggered interupts on a PIC (specifically a 16F690)

i'd dearly love to be able to use Darrel's simple routines...but I'm a little clueless wrt ensuring I'm connecting my incoming 'pulses' to the correct PIC 16F690 pins!

edit: Darrel has kindly replied to the earlier PM I sent him, telling me that I need to look for the pin marked 'INT'...which on my PIC 16F690 is apparently pin RA2 - tks Darrel!

[Jumper]

Hi,

If you have a T?CKI pin on your pic you can use that pin to check for black stripes. This is the pin for the external clock signal connected to the internal timer/counter. This way you can get an interupt every black stripe or every 2:nd or once per wheel rotation (or anything else more or less). This is all depending of what you preload the counter with. If you have a 8-bit counter and load FF into it, next clock pulse will overflow the counter and you will get an interupt. If you preload it with FF-(dec 48) it will overflow once every full rotation of the wheel.

If you just want to count the stripes preload it with 0 and off you go....

This way your PIC will do most of the counting by itself and giving you more instruction time for something more useful.

If you use the RA2/INT for the magnetic switch you can use RA5/T1CKI the external clock input for the stripes phototransistor

/me

[HankMcSpank]

Hi,

If you have a T?CKI pin on your pic you can use that pin to check for black stripes. This is the pin for the external clock signal connected to the internal timer/counter. This way you can get an interupt every black stripe or every 2:nd or once per wheel rotation (or anything else more or less). This is all depending of what you preload the counter with. If you have a 8-bit counter and load FF into it, next clock pulse will overflow the counter and you will get an interupt. If you preload it with FF-(dec 48) it will overflow once every full rotation of the wheel.

If you just want to count the stripes preload it with 0 and off you go....

This way your PIC will do most of the counting by itself and giving you more instruction time for something more useful.

If you use the RA2/INT for the magnetic switch you can use RA5/T1CKI the external clock input for the stripes phototransistor

/me

Thanks...there's some top tips there.

Just a thought here - is it even possible to get reliable results with mechanical switches & interupts?

By this I mean, a mechanical switch normally needs a debounce, else you'd get more than one interupt for every time the switch 'settled'? In my situation, it's importnat that there's just one 'trigger' for every revolution of the encoder wheel (so I can establish how many interupts/black stripes the PIC has counted over one rev)...if I used an interupt for the magnetic switch, there'd be a possibility of not just one interupt...but several in quick succession...which will cause a bit of 'fog' whilst trying to confirm that my wheel, circuit & PIC are all in sync & counting 48 stripes per turn!

By the way...I've now dabbled with Darrel's "Hello World" which will suit my encoder wheel needs perfectly....after wrestling with 'pin' polling for weeks with my encoder wheel & getting very erratic results, I'm one very happy McSpank here today! October 05, 2002 maybe was a good day...but I can say without any shadow of a doubt, for me the 19 May 2009 was a lot better !!

Just a couple of small suggestions for Darrel's website (to save avoid a lot of newbie-esque puzzlement) - on Darrel's very first hello world code page, it might be worth saying that a user will need to establish their own PIC variant's 'INT' pin, along with perhaps a couple of PIC specific examples. (it might be ovbious to you old hands, but looking at the plethora of pins PICs have, it wasn't obvious to me!)

Also, for what it's worth...the 16F690 is perhaps the most common chip that newbies come into contact with at the moment (on account it's bundled with Microchip's very popular PikKit2 starter kit)...I had a problem with Darrel's "Hello World" code when I first compiled ...."error: variable wsave3 position request 416 beyond ram_end 367.", ultimately meaning a line in Darrel's DT_INTS-14.bas file needed commenting out - that might also be worth a mention too? (or at least some mention on a FAQ page?)

Anyway, a hearty thanks to Darrel... without his effort towards making interupts easy with PICBasic , I'm sure I would have left interupts for another day (ie sometime in 2023!)